Aluminum chloride-catalyzed reaction of tetrachloromethylpropane



CHLORIDEPCATALY-ZED REAGTION. F TETRACHLQROM'ETHYLPROPANE n l G. Kun and H e P ed e, Ju, Man a a Karts, assignors to The Dow Ghem'ical ,Qqmpany, Midland, Mich, a corporation of Delaware o D a in Amman Mu h 1.1. 1 .3.

'seri us .s41,s3 4 .1

6 Claims c1. 260-651 This invention is concerned with S-aryl-Ll-dichloro- Z-methylpropenes and is particularly directed to amethod for reacting l,1,1,2:tetrachloro-2-methylpropane with certain aromatic compounds in the presence of aluminum chloride to produce 3-aryl-l,l-dichloroQ-methyh.

propenes. The latter compounds have been found valuable as toxic constituents of aqueous spray compositions for the control of insect and mite pests.

According to the present invention it has been .discovered that 1,1,1,2-tetrachloro12:methylpropane, having the formula 1: .OhG-IErOH:

may be reacted with certain aromatic compounds in the presence of a catalytic amount of anhydrous aluminum chloride and at temperatures offrom about 70 to 100 C. to produce 3-aryl-1,1-dichloro-2-methyl-l-propenes. The term aromatic compound as herein employed is particularly intended to include substituted benzenes capable of condensation with alkyl chlorides in the Friedel-Crafts reaction.

In carrying out the invention, the aromatic compound and catalyst are mixed together and heated to the reaction temperature and the 1,1,1,2-tetrachloro-2-methylpropane added thereto portionwise with stirring. At least one molecular proportion of aromatic compound is employed for each molecular proportion of tetrachloromethylpropane in the reaction and it is preferred to employa considerable excess of the aromatic reactant, said excess serving as a reaction solvent. In the latter case, it is convenient to employ a portion of the excess aromatic reactant as a solvent for the tetrachloromethylpropane to facilitate the addition thereof. It is preferred to employ as the aromatic reactant a material which is liquid at the reaction temperature, however, higher melting aromatic compounds may be utilized by using a suitable inert solvent as the reaction medium.

The reaction proceeds with the evolution of hydrogen chloride and is conveniently carried out in a vessel lined with glass, porcelain, nickel, stainless steel or other material resistant to the corrosive action of hydrogen chloride. The reaction vessel may be vented into a trap or scrubber for the recovery of the hydrogen chloride evolved. The exact equipment is not critical and may range from a simple pot reactor to a system run on a continuous or semi-continuous basis with any unreacted portion of either organic reactant being recovered and recycled in the system.

The reaction proceeds satisfactorily at atmospheric pressures, although somewhat elevated or reduced pressures may be employed if desired. 7

The reaction is exothermic and the rate increases with increasing temperature. The reaction is initiated and proceeds rapidly when the reactants are brought together in the presence of the catalyst as set forth above and the rate may be controlled to a considerable extent by the rate of admixture of the reactants. While the radical of from 1 to 4 carbon atoms, inclusive, to produc a compound of the formula r 2,778,861 Patented Jan. 22, L957 act n operable a temp ratu es c tramout 70 to it is p eter esl'to ca r gut he eaa op at from about to C. Highertemperatures are 9 b ayg d d in orde o t forma p tarry by-products.

While any operable proportions of the aluminum of tarry by-products. Generally 0.01 to 0.04 mole of the aluminum chloride in relation to one mole of this tetrachloropropane was most effective.

Th P.IQ@ .F-$ 9f t e %??299 ma be se ar t d y qgnveut p a1. .ptqcadure ncas 295 Q! g etat on e .rc s i new i a de 0 amiature'gf F u hed i and a strong" n r l a to -d.Q r P9 eth. -el min m hla s e wtal st. the result sg m x re eparat n nt an quaqus a e a d. a oi y crsanis r.- The or an layer is separated and the aqueous layer extracted with ether. The organic layer and ether extracts arecomll l and the ethe e p erad b di i la sn- Th P d acts o th react au a e en sepa a ed and unreeqt d tart n ma er als .IQQQYQEQ by t astisua d s l a on 1 1 der reduced pressure. 7 v

In a representative operation 2.6 grams (0.02 mole) of anhydrous aluminum chloride and 300 grams (2.66 moles) of chlorobenzene were mixed together and heated to a temperature of 90 to 99 C. To the resulting mix ture 88 grams (0.5 mole) of 1,l,1,2-tetrachloro-2- methylpropane dissolved in 262.5 grams (2.33 moles) of chlorobenzene was added portionwise with stirring over a period of 1.25 hours. The reaction mixture was maintained at 90 to 99 C. throughout this period. The reaction mixture was then poured into a mixture of crushed ice and concentrated hydrochloric acid, the resulting mixture separating into an organic layer and an acidic aqueous layer. The organic layer was separated and the aqueous layer extracted with ether. The organic layer and ether extracts were then combined and submitted to fractional distillation under reduced pressure to recover the solvent and unreacted starting materials and to separate a parachlorophenyl 1,1-dichloro-2- methyl-l-propene product boiling at 91 to 97 C. under a pressure of 0.3 millimeter.

In a similar fashion, 1,l,1,2-tetrachloro-2-methylpropane is reacted in the presence of a catalytic amount of aluminum chloride with bromobenzene, toluene, in xylene, or tertiarybutylbenzene to produce p-bromophenyl 1,1 dichloro 2 methylpropene, p-tolyl-1,1-dichloro-2- methyl l propene, 2,4 dimethylphenyl-1,1-dichloro-2- methyl-l-propene or p-tertiarybutylphenyl-l,l-dichloro- Z-methyl-l-propene, respectively.

A preferred embodiment of the invention comprises reacting 1,l,1,2-tetrachloro-Z-methylpropane in the presence of a catalytic amount of anhydrous aluminum chloride with a compound of the formula wherein R represents bromine, chlorine or a lower alkyl CH3 Cl or wherein R has the significance as set forth above;

3 The aryl-dichloro-methylpropene products may be dissolved in xylene together with a non-ionic emulsifying agent to prepare emulsifiable concentrates adapted to be dispersed in water for producing aqueous spray compositions. These compositions are effective for the con trol of mite and aphid pests on vegetation.

We claim:

1. A method for preparing compounds having the formula CH2. O1

R CHPaO wherein R is selected from the group consisting of chlorine, bromine and lower alkyl radicals of from 1 to 4 carbon atoms, inclusive, which comprises reacting 1,1,1,2-tetrachloro-2-methylpropane with a compound of the formula v 4 benzene in the presence of a catalytic amount of anhydrous aluminum chloride and at a temperature of from about 70 to 100 C.

4. A method for the preparation of 3-(parabromophenyl)-1,l-dichloro 2 methyl-l-propene which comprises reacting 1,1,1,2-tetrachloro-2-methylpropane with br'omobenzene in the presence of a catalytic amount of anhydrous aluminum chloride and at a temperature of from about 70 to 100 C.

5. A method for the preparation of 3-(paratolyl)-1,1- dichloro-Z-methyl-l-propene which comprises reacting 1,1,1,Z-tetrachloro-2-rnethylpropane with toluene in the 7 presence of a catalytic amount of anhydrous aluminum References Cited in the file of this patent UNITED STATES PATENTS Joyce Nov. 5, 1946 Schmerling Oct. 18, 1949 OTHER REFERENCES Huntress, Organic Chlorine Compounds, pp. 728-9, 1948). 

1. A METHOD FOR PREPARING COMPOUNDS HAVING THE FORMULA 